1. Field of the Invention
The present invention relates to a field emission type electron emission device using an electron emission film, an electron source having a number of the electron emission devices, and an image display constructed using the electron source.
2. Description of the Related Art
The electron emission device includes a field emission type (referred to as an FE type below) and a surface conduction type electron emission device.
The FE type electron emission device is a device for extracting electrons into a vacuum from a cathode electrode (or the electron emission film) by applying a voltage (electric field) between the cathode electrode (and the electron emission film disposed thereon) and a gate electrode. Therefore, the operating electric field is largely affected by the work function and the shape of the cathode electrode (the electron emission film), and in general, the cathode electrode (the electron emission film) with a small work function may be necessary to be selected.
Japanese Patent Laid-Open No. 9-199001 discloses an electron emission device having a metal as the cathode electrode and a semiconductor (diamond, AlN, BN, etc.) bonded to the metal. In that Japanese Patent, a method is disclosed in which the semiconductor film surface of diamond with a thickness of about 10 nm or less is terminated with hydrogen so as to make negative on electron affinity of the semiconductor film. FIG. 14 is a band diagram showing the electron emission principle of the electron emission device disclosed in Japanese Patent Laid-Open No. 9-199001. In the drawing, reference numeral 1 denotes the cathode electrode, numeral 141 the semiconductor film, numeral 3 an extraction electrode, numeral 4 a vacuum barrier, and numeral 6 an electron.
Diamond having a surface terminated with hydrogen is typical as a material having a negative electron affinity. An electron emission device using a diamond surface as an electron emission surface is disclosed in U.S. Pat. No. 5,283,501, U.S. Pat. No. 5,180,951, Zhinov. J. Liu et al, “Environmental Effect On the electron emission from diamond surfaces”, and J. Vac. Sci. Technol, B16(3), May/June, 1998, PP. 1188–1193.